Findings from a wide variety of biological systems indicate that transcriptional regulation plays a key role in the expression of numerous genes involved in growth and development. A large number of positive and negative transcription factors are involved in controlling these processes and the interplay of these factors is critical for the proper expression of genetic information. In the past few years, results from a number of studies revealed that DNA binding proteins are centrally involved in mediating correct interactions among regulatory proteins. I am interested in investigating the proper6ties and function of a protein in Escherichia coli, integration host factor (IHF), as a model protein for studying interactions among proteins in the regulation of gene expression in all systems. Studies will focus on characterizing the role of IHF in the expression of ompF an operon required for the synthesis of a major outer membrane protein ompF. Biochemical and genetic experiments will be used to address the following questions: . Does IHF play a major role in the osmoregulation of this operon? 2. Does IHF effect osmoregulation through effects on OmpR, the transcription factor that mediates osmoregulation of ompF? 3. Is alteration in DNA structure by IHF critical for its role in ompF expression?